internal/rosa: replace busybox with toybox

The busybox artifact does not run on aarch64, and the workarounds required for it to compile successfully on x86_64 is unacceptably shaky. This change fully replaces it with toybox.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/rosa.go

@@ -190,7 +190,7 @@ func (t Toolchain) New(
 
 	var (
 		path    = AbsSystem.Append("bin", "sh")
-		args    = []string{"mksh", absCureScript.String()}
+		args    = []string{"sh", absCureScript.String()}
 		support []pkg.Artifact
 	)
 	switch t {
@@ -255,7 +255,7 @@ ln -vs ../usr/bin /work/bin
 			runtimes,
 			clang,
 			boot.Load(Mksh),
-			boot.Load(Busybox),
+			boot.Load(Toybox),
 		})
 		env = fixupEnviron(env, []string{
 			EnvTriplet + "=" + triplet(),